To investigate whether the active transport of bicarbonate across the corneal endothelium occurs: the flux of bicarbonate and chloride across this layer will be compared when the fluid pump is operating and when it is inhibited. To identify the pathway by which water is pumped across the endothelium, through the cytosol, in vesicles or in the paracellular spaces: evidence of the first will be changes in cell volume; the second, rapid labelling of vesicles with electronopaque markers; the third more rapid diffusion of a tracer downstream than upstream. To examine the possibility of using tissue cultured endothelial cells in keratoplasty: cultured cells will be plated on stromal buttons for grafting in rabbits; the potentiality of human cells to grow in cultures will explored. To identify the cells which produce chemical stimulators of vascular invasion in the cornea: the effect of corneal lesions on the vascularization of normal, leukopenic and animals without their corneal epithelium will be compared. To identify the chemical agents which evoke vascularization: biologically active materials will be slowly injected into the cornea and the resulting vascular activity compared with that of lesions. To study the formation of mucus by the goblet cells of the conjunctiva: autoradiography of SO4 incorporation will be carried out, formation will be observed in vivo and by electron microscopy.